Conventionally, a known vehicle has a rechargeable battery as a power source for accumulating an electric energy for traveling. In particular, a plug-in vehicle is configured to charge a rechargeable battery from a power supply outside the self-vehicle. For example, an electric vehicle (EV) and a plug-in hybrid vehicle (PHV) are known as examples of a plug-in vehicle. There are multiple proposed arts for charging a rechargeable battery of a plug-in vehicle. For example, Japanese unexamined patent application publications 2008-117444, 10-80071, and 2008-247080 disclose arts for charging multiple vehicles from one power supply source. Specifically, Japanese unexamined patent application publication 2008-117444 discloses an electric supply apparatus in which rechargeable batteries of multiple vehicles are connected in parallel with a power supply source for simultaneously charging the rechargeable batteries. In this case, the power supply source needs to have a large capacity in order to charge the rechargeable batteries simultaneously. In this case, a user having the electric supply apparatus needs to make a contract with an electric power company to consume a large electric power. Consequently, a basic contract fee for electricity may become high. On the other hand, Japanese unexamined patent publication 10-80071 discloses a control to shift charge time points of multiple vehicles so as to suppress the capacity of a power supply source. Specifically, an order of charge of second batteries are determined according to charge time periods of the rechargeable batteries. However, the order of charge of the second batteries determined according to the charge time periods does not necessarily reflect an intention of a user of a vehicle.